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Zhang B, Zhang L, He L, Yang X, Shi Y, Liao S, Yang S, Cheng J, Ren T. Interactions of Fipronil within Fish and Insects: Experimental and Molecular Modeling Studies. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:5756-5761. [PMID: 29627978 DOI: 10.1021/acs.jafc.8b00573] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Fipronil is an efficient phenylpyrazole insecticide that acts on insect γ-aminobutyric acid (GABA) receptors (GABARs) and has low toxicity to mammals but high toxicity to nontarget organisms such as fish. To develop novel efficient low-toxicity insecticides, it is necessary to determine the detailed toxic mechanism at the molecular target level. In this work, methods including affinity chromatography, fluorescent-labeled binding assays, and molecular modeling were integrated to explore the binding of fipronil to GABARs in fish ( Aristichthys nobilis) and insects ( Musca domestica). Affinity chromatography revealed that fipronil acts on two different subunits of GABARs in fish and M. domestica. Moreover, fluorescence assays revealed that fipronil exhibits similar affinity to the two GABARs. The Kd and Bmax of fipronil binding to the A. nobilis GABAR were 346 ± 6 nmol/L and 40.6 ± 3.5 pmol/mg of protein, respectively. And the Kd and Bmax of fipronil binding to the GABAR in M. domestica brain were 109 ± 9 nM and 21.3 ± 2.5 pmol/mg of protein, respectively. In addition, similar fipronil binding positions but different binding modes were observed in docking studies with Brachydanio rerio var. and M. domestica GABARs. These findings indicated similar interactions of fipronil with fish and insects, leading to high toxicity. The different binding features of fipronil between the two species might be helpful for the design and development of highly selective insecticides with low toxicity to fish.
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Affiliation(s)
- Bo Zhang
- The Key Laboratory of Resource Chemistry of Ministry of Education, The Development Centre of Plant Germplasm Resources, College of Life and Environmental Science , Shanghai Normal University , 100 Guilin Road , Shanghai 200234 , P.R. China
| | - Lei Zhang
- The Key Laboratory of Resource Chemistry of Ministry of Education, The Development Centre of Plant Germplasm Resources, College of Life and Environmental Science , Shanghai Normal University , 100 Guilin Road , Shanghai 200234 , P.R. China
| | - Lujue He
- Shanghai Key Laboratory of Chemical Biology, Shanghai Key Laboratory of New Drug Design, School of Pharmacy , East China University of Science and Technology , 130 Meilong Road , Shanghai , 200237 , P.R. China
| | - Xiaodong Yang
- The Key Laboratory of Resource Chemistry of Ministry of Education, The Development Centre of Plant Germplasm Resources, College of Life and Environmental Science , Shanghai Normal University , 100 Guilin Road , Shanghai 200234 , P.R. China
| | - Yali Shi
- The Key Laboratory of Resource Chemistry of Ministry of Education, The Development Centre of Plant Germplasm Resources, College of Life and Environmental Science , Shanghai Normal University , 100 Guilin Road , Shanghai 200234 , P.R. China
| | - Shaowei Liao
- The Key Laboratory of Resource Chemistry of Ministry of Education, The Development Centre of Plant Germplasm Resources, College of Life and Environmental Science , Shanghai Normal University , 100 Guilin Road , Shanghai 200234 , P.R. China
| | - Shan Yang
- The Key Laboratory of Resource Chemistry of Ministry of Education, The Development Centre of Plant Germplasm Resources, College of Life and Environmental Science , Shanghai Normal University , 100 Guilin Road , Shanghai 200234 , P.R. China
| | - Jiagao Cheng
- Shanghai Key Laboratory of Chemical Biology, Shanghai Key Laboratory of New Drug Design, School of Pharmacy , East China University of Science and Technology , 130 Meilong Road , Shanghai , 200237 , P.R. China
| | - Tianrui Ren
- The Key Laboratory of Resource Chemistry of Ministry of Education, The Development Centre of Plant Germplasm Resources, College of Life and Environmental Science , Shanghai Normal University , 100 Guilin Road , Shanghai 200234 , P.R. China
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E. coli-Based Cell-Free Expression, Purification and Characterization of the Membrane-Bound Ligand-Binding CHASE-TM Domain of the Cytokinin Receptor CRE1/AHK4 of Arabidopsis thaliana. Mol Biotechnol 2010; 47:211-9. [DOI: 10.1007/s12033-010-9331-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Rodgers G, Hubert C, McKinzie J, Suter T, Statnick M, Emmerson P, Stancato L. Development of displacement binding and GTPgammaS scintillation proximity assays for the identification of antagonists of the micro-opioid receptor. Assay Drug Dev Technol 2004; 1:627-36. [PMID: 15090235 DOI: 10.1089/154065803770380986] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This article describes the development of micro-opioid receptor (MOR) binding and GTPgammaS functional SPAs as improved screening tools for the identification of MOR antagonists. Opioid receptors are members of the seven-transmembrane G protein-coupled receptor (GPCR) family and are involved in the control of various aspects of human physiology, including pain, stress, reward, addiction, respiration, gastric motility, and pituitary hormone secretion. Activation of the MOR initiates intracellular signaling pathways leading to a reduction in intracellular cyclic AMP levels, inhibition of calcium channels, and activation of potassium channels resulting in a reduction of the excitability of neurons. Characterization of opioid receptor ligand binding has traditionally been accomplished through the use of low throughput filtration-based binding assays, whereas functional activity has been based upon cyclic AMP measurements or filtration-based GTPgammaS functional assays. This report describes the development of a MOR displacement binding SPA using the radiolabeled antagonist [(3)H]diprenorphine ((3)H-DPN). The assay was optimized using statistical experimental design and demonstrates the stability and robustness necessary for HTS. The assay was biased toward the identification of MOR antagonists through the addition of Na(+). Our assay conditions also minimized the phenomenon of ligand depletion, a problem commonly observed in low-volume assays using high receptor-expressing cell lines. The optimized procedure revealed (3)H-DPN affinity constants at the MOR that were consistent with results obtained using filtration methods (K(D) (SPA) = 1.89 +/- 0.24 nM, K(D) (filtration) = 1.88 +/- 0.35 nM). The binding SPA identified known opioid receptor modulators contained within the Library of Pharmacological Active Compounds (LOPAC) cassette, and the GTPgammaS scintillation proximity assay (SPA) was used to confirm the functional activity of the LOPAC antagonists acting at the MOR. Conversion of the ligand binding and GTPgammaS functional assays to a homogeneous SPA generated a simple assay with dramatically increased throughput. Data from the development and implementation of the displacement binding and GTPgammaS functional SPAs are presented.
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Affiliation(s)
- George Rodgers
- Eli Lilly and Company - Lilly RTP, Research Triangle Park, NC 27709, USA.
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Janssen MJ, Ensing K, de Zeeuw RA. A fluorescent receptor assay for benzodiazepines using coumarin-labeled desethylflumazenil as ligand. Anal Chem 2001; 73:3168-73. [PMID: 11467569 DOI: 10.1021/ac001480f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This article describes a novel nonisotopic receptor assay for benzodiazepines with fluorescence detection. As labeled ligand (coumarin-labeled desethylflumazenil, CLDEF), a metabolite of the benzodiazepine antagonist flumazenil (desetheylflumazenil, Ro15-3890) has been coupled to a coumarin fluorophore, via a spacer. CLDEF had a Ki of 6.5 nM. To avoid the interference of the background fluorescence of the receptors in the measurement step, the bound CLDEF was dissociated from the receptors after the filtration step. This dissociation was achieved by incubating the CLDEF-bound to the receptors on the filters-with a weakly acetate buffer. The second filtrates then contained the previously bound CLDEF, which was then quantitated with a RP-HPLC system with a fluorescence detector. The results with a fluorescent receptor assay were very similar to those with a radioreceptor assay, in that the IC50 values of lorazepam were 7.2 +/- 0.5 and 6.6 +/- 0.7 nM, respectively.
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Affiliation(s)
- M J Janssen
- University Centre for Pharmacy, Department of Analytical Chemistry and Toxicology, Groningen, The Netherlands
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Janssen MJ, Ensing K, de Zeeuw RA. Improved benzodiazepine radioreceptor assay using the MultiScreen Assay System. J Pharm Biomed Anal 1999; 20:753-61. [PMID: 10701983 DOI: 10.1016/s0731-7085(99)00090-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In this article, an improved benzodiazepine radioreceptor assay is described, which allows substantial reduction in assay time. The filtration in this method was performed by using the MultiScreen Assay System. The latter consists of a 96-well plate with glass fibre filters sealed at the bottom, which allows both the incubation and the filtration of the specimen in the same plate. After the filtration, the filters were punched out for quantitation of the bound labeled ligand [3H]flunitrazepam. The results obtained with the MultiScreen Assay System did not differ significantly from the data obtained with the conventional filtration manifold (48S): The Ki's of lorazepam were 2.4 +/- 0.30 and 1.9 +/- 0.15 nM, respectively. In case a radioactive label is replaced by a fluorescent label, the bound labeled-ligand usually cannot be determined in the presence of the receptor material. Here, the bound labeled-ligand has to be dissociated after the filtration step. To dissociate the ligand-receptor complex, Tris- HCl buffer, containing 10 microM flumazenil, was added to the filters and the second filtrates were collected containing the previously bound fractions in the absence of receptor material. This approach showed the same Ki for lorazepam, 2.5 +/- 0.04 nM as without dissociation, when using the radio-labeled benzodiazepine [3H]flunitrazepam.
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Affiliation(s)
- M J Janssen
- Department of Analytical Chemistry and Toxicology, Groningen Institute for Drug Studies, University Centre for Pharmacy, The Netherlands
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Viel GT, Yang Q, Lundahl P, Ensing K, de Zeeuw RA. Size-exclusion chromatographic reconstitution of the bovine brain benzodiazepine receptor. Effects of lipid environment on the binding characteristics. J Chromatogr A 1997; 776:101-7. [PMID: 9286083 DOI: 10.1016/s0021-9673(97)00428-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The benzodiazepine receptor from calf brain was solubilized with sodium deoxycholate (2 mg/ml) in the presence of 0.5 M KCl and protease inhibitors, and bound flunitrazepam with an equilibrium dissociation constant (Kd) of 2.7 +/- 1.2 nM and with 0.40 +/- 0.04 pmol binding sites per mg protein (Bmax). Up to 60% of the benzodiazepine binding sites (average 25%) could be reconstituted in lipid vesicles, upon size-exclusion chromatography of protein-detergent-lipid mixtures on Sephadex G-50 Medium for detergent depletion. The flunitrazepam affinity for the reconstituted receptor varied with the lipid composition (Kd 1.4-4 nM). Freezing and thawing increased the size of the small proteoliposomes obtained by chromatographic reconstitution and, on the average, doubled the number of operative flunitrazepam binding sites. When the proteoliposomes were stored at -20 degrees C or -80 degrees C or in lyophilized state, the receptor retained its benzodiazepine binding affinity and Bmax over a period of 2 months.
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Affiliation(s)
- G T Viel
- Groningen Institute for Drug Studies (GIDS), Department of Analytical Chemistry and Toxicology, The Netherlands
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